Organic carbon distribution and isotopic composition in three records from the eastern Mediterranean Sea during the Holocene

Katsouras, G.; Gogou, Alexandra; Bouloubassi, Ioanna; Emeis, Kay–Christian; Triantaphyllou, Maria; Roussakis, Grigoris; Lykousis, V.

doi:10.1016/j.orggeochem.2010.04.008

Cited by 23 publications

(20 citation statements)

References 28 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…The pronounced interruption of sapropel deposition in our Adriatic site sedimentary record at 8.2 cal ka BP and in published Aegean records [e.g. De Rijk et al, 1999;Gogou et al, 2007;Kotthoff et al, 2008a;Ní Fhlaithearta et al, 2010;Geraga et al, 2010;Katsouras et al, 2010] connotes the widespread climate deterioration that, despite its short duration, has caused the resumption of Mediterranean deep-water formation.…”

Section: Consequences For Deep-basin Ventilationsupporting

confidence: 60%

Eastern-Mediterranean ventilation variability during sapropel S1 formation, evaluated at two sites influenced by deep-water formation from Adriatic and Aegean Seas

Filippidi

Triantaphyllou

Lange

2016

Quaternary Science Reviews

View full text Add to dashboard Cite

a b s t r a c tPresent-day bottom-water ventilation in the Eastern Mediterranean basin occurs through deep-water convection originating from the two marginal basins, i.e. Adriatic and Aegean Seas. In the paleo record, long periods of enhanced deep-water formation have been alternating with shorter periods of reduced deep-water formation. The latter is related mainly to low-latitude humid climate conditions and the enhanced deposition and preservation of organic-rich sediment units (sapropels). This study focuses on sedimentary archives of the most-recent sapropel S1, retrieved from two sites under the direct influence of the two deep-water formation areas. Restricted oxygen conditions have developed rapidly at the beginning of S1 deposition in the Adriatic site, but bottom-water conditions have not persistently remained anoxic during the full interval of sapropel deposition. In fact, the variability in intensity and persistence of sedimentary redox conditions at the two deep-water formation sites is shown to be related to brief episodes of climate cooling. In the Adriatic site, sapropel deposition appears to have been interrupted twice. The 8.2 ka event, only recovered at the Adria site, is characterized by gradually increasing suboxic to possibly intermittently oxic conditions and decreasing C org fluxes, followed by an abrupt re-establishment of anoxic conditions. Another important event that disrupted sapropel S1 formation, has taken place at ca. 7.4 cal ka BP. The latter event has been recovered at both sites. In the Adriatic site it is followed by a period of sedimentary conditions that gradually change from suboxic to more permanently oxic, as deduced from the Mn/Al pattern. Using the same proxy for suboxic/oxic sedimentary redox conditions, we observe that conditions in the Aegean Sea site shift to more permanently oxic from the 7.4 ka event onwards. However, at both sites the accumulation and preservation of enhanced amounts of organic matter have continued under these suboxic to intermittently oxic sedimentary conditions. It seems thus, that after 7.4 cal ka BP sapropel-like surface or deep-chlorophyllmaximum conditions including enhanced productivity continued, whereas bottom-water conditions were at least intermittently oxic. The latter is related to decreasing precipitation, i.e. run-off, and thus a progressive development and deepening of deep-water formation. The shallower Aegean site, would be affected earlier by such deepening ventilation than the slightly deeper Adriatic site. Finally, termination of sapropel S1 formation as deduced from diminished organic matter contents and Ba/Al, appears to have occurred almost simultaneously in the two areas, namely at 6.6 ± 0.3 and 6.3 ± 0.5 cal ka BP in Adriatic and Aegean sites, respectively.

show abstract

Section: Consequences For Deep-basin Ventilationsupporting

confidence: 60%

Eastern-Mediterranean ventilation variability during sapropel S1 formation, evaluated at two sites influenced by deep-water formation from Adriatic and Aegean Seas

Filippidi

Triantaphyllou

Lange

2016

Quaternary Science Reviews

View full text Add to dashboard Cite

show abstract

“…Higher values of OC during the deposition of S1a than those of S1b indicate highest organic matter production and preservation in S1a, supporting previous results in the Aegean area (e.g., Gogou et al, 2007;Triantaphyllou et al, 2009b;Katsouras et al, 2010). The almost constant values of δ 13 C org during S1a, confirm the hypothesis that the deposition of sapropel S1 depends on primary productivity and preservation of organic matter (Katsouras et al, 2010). During the depositions of S1a and S1b the dominant planktonic species are T. quinqueloba and G. bulloides (Figure 4).…”

Section: Discussionsupporting

confidence: 87%

“…This is accompanied by decrease in OC and the presence of planktonic foraminifera assemblages which suggest stronger mixing of the water column at least during winter. The more negative values of δ 13 C org identified at 7.7 Ka BP (-26.1 ‰) are indicative of terrigenous organic matter (e.g., Meyers & Arnaboldi, 2008;Katsouras et al, 2010) that may caused high value (1.26%) of OC, during the interruption interval.…”

Section: Discussionmentioning

confidence: 95%

“…The positive shift of the Aegean Sea's freshwater budget during sapropel deposition -possibly supplemented by enhanced freshwater inputs from the Southern European margin (Kotthoff et al, 2008) -weakened the basin's deepwater circulation and resulted in oxygen starved conditions at the seafloor. Recent paleoceanographic findings (e.g., Gogou et al, 2007;Triantaphyllou et al, 2009 a,b;Katsouras et al, 2010;Kouli et al, 2012) suggest that during the Holocene, a rather mild climatic period, between 10 and 6 kyr BP, appeared in the sediments through the deposition of the most recent sapropel layer S1. Besides the monsoonal system, precipitation and inflow of Black Sea waters may have also contributed in modifying the freshwater budget during times of S1 formation (e.g., Kuhnt et al, 2007).…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Preliminary results of high resolution paleoceanography and paleoclimatology during sapropel S1 deposition (South Limnos Basin, North Aegean Sea).

et al. 2016

View full text Add to dashboard Cite

The paleoenviromental conditions during the depositional interval of sapropel S1 in the northeastern Aegean (gravity core M-4, length 2.53 m; south Limnos basin) are studied based on quantitative micropaleontological (benthic and planktonic foraminifera) and geochemical (OC, δ13Corg) analyses. Special feature of core M-4 is the thickness of S1 layer (96 cm). Our study points that sapropelic layer S1a has been deposited in more dysoxic and warmer conditions in respect to S1b. Both primary productivity and preservation of organic material are more intense during the lower part of S1. An interruption of the sapropelic conditions at 8.0 Ka BP which is mainly characterized by the increase of agglutinated foraminiferal forms confirms both higher oxygen bottom conditions and freshwater input.

show abstract

“…In fact, sapropels respond to periods of enhanced freshwater flux (e.g., Rohling and Hilgen 1991;Bar-Matthews et al 2000;Kallel et al 2000) during periods of strong summer insolation (e.g., Rohling 1994;Rohling et al 2002;Meyers 2006). Evidence from eastern Mediterranean Quaternary sapropel studies indicate that freshwater stratification and organic carbon accumulation took place due to both enhanced productivity and hypoxia, during warm and wet climatic conditions (e.g., De Lange and Ten Haven 1983;Emeis et al 2000a;Casford et al 2003;Gogou et al 2007;De Lange et al 2008;Kuhnt et al 2008;Triantaphyllou et al 2009aTriantaphyllou et al , b, 2010Triantaphyllou et al , 2013Katsouras et al 2010;Schmiedl et al 2010;Kouli et al 2012;Triantaphyllou 2014).…”

Section: Introductionmentioning

confidence: 99%

Zanclean/Piacenzian transition on Cyprus (SE Mediterranean): calcareous nannofossil evidence of sapropel formation

et al. 2015

View full text Add to dashboard Cite

Quantitative analyses of calcareous nannofossils in the sediments of Pissouri South section on the island of Cyprus have produced a paleoceanographic record reflecting the paleoclimatic conditions during the Zanclean/Piacenzian transition. Pissouri South cyclical lithological alternations between organic-rich laminated layers and grey marls reflect the Earth's orbital precession. According to the calcareous nannofossil biostratigraphy which has been performed, the studied section is correlated with MNN14/15 and MNN16 calcareous nannofossil biozones and is astronomically dated between 4.065 and 3.217 Ma. Intervals of increased organic carbon content, along with the positive values of Florisphaera profunda, Helicosphaera sellii, Discoaster spp. and the subsequent increase of stratification S-index, correspond to the sapropel deposition during periods of wetter climate and intense continental runoff, especially from the river Nile. These layers alternate with grey marly intervals, featured by the increased values of small placoliths of Reticulofenestra and Gephyrocapsa species, which are indicative of eutrophic conditions during intense surface-water mixing. Our data support the prevalence of a generally warm phase characterized by the absence of high-frequency climate variations in the southeastern Mediterranean during the Zanclean/Piacenzian (Early/Late Pliocene) transition.

show abstract

Organic carbon distribution and isotopic composition in three records from the eastern Mediterranean Sea during the Holocene

Cited by 23 publications

References 28 publications

Eastern-Mediterranean ventilation variability during sapropel S1 formation, evaluated at two sites influenced by deep-water formation from Adriatic and Aegean Seas

Eastern-Mediterranean ventilation variability during sapropel S1 formation, evaluated at two sites influenced by deep-water formation from Adriatic and Aegean Seas

Preliminary results of high resolution paleoceanography and paleoclimatology during sapropel S1 deposition (South Limnos Basin, North Aegean Sea).

Zanclean/Piacenzian transition on Cyprus (SE Mediterranean): calcareous nannofossil evidence of sapropel formation

Contact Info

Product

Resources

About